A wind turbine comprises a rotor that is equipped with rotor blades. The rotor converts the energy of the moving air into rotational energy of the rotor that is then transformed into electrical energy in the generator of the wind turbine.
The rotor blades are connected to the hub of the rotor in a way that they can be rotated around their longitudinal axis. Thus the rotor blades can perform a pitch movement relative to the hub.
The pitch movement is needed to control the rotational speed of the rotor and the performance of the wind turbine.
When the wind turbine is not in operation, the rotor blades are arrested in a stop position.
In an emergency situation the rotor of a wind turbine needs to be stopped in a short time. To quickly stop the rotation of the rotor, the rotor blades are pitched into a stop position. In this stop position the aerodynamic shape of the rotor blades is no longer used to support the rotation of the rotor. In addition the rotor blades interact with the surrounding air in a way that the rotational speed of the rotor is decreased.
An emergency situation in a wind turbine might occur due to the loss of the grid connection or a technical problem like the loss of a viable technical system.
In an emergency situation the rotor blades are locked in the stop position. The rotor blades are locked mechanically in a way that no further energy is needed to maintain the rotor blades in the locked position.
The locking mechanism of a rotor blade comprises a click-stop device, to allow the rotor blade to enter the locking position, but not to leave the locking position in at least one direction.
It is known to build a locking mechanism with a pawl, a ramp, and a notch. The pawl slides along the ramp to enter the notch. Once the pawl arrests in the notch the position of the rotor blade is locked.
The parts are mounted to a base, for example to a reinforcement plate of the blade bearing.
This shows the disadvantage, that several parts need to be mounted in the wind turbine, and that the parts need to be controlled and maintained during service to ensure their proper function.
In addition bending moments are introduced into the plate, as the parts comprise a lever when the locking pawl is acting on the parts building the ramp and providing the notch. Thus the reinforcement plate needs to be built rigid enough to withstand the bending moments introduced into the plate.
The aim of embodiments of the invention is therefore to provide an improved arrangement of a locking mechanism.